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==============================
Use assert statements in tests
==============================
.. autoplugin :: nose2.plugins.prettyassert.PrettyAssert
assert statement inspection
---------------------------
The prettyassert plugin works by inspecting the stack frame which raised an
`AssertionError`. Unlike pytest's assertion rewriting code, it does not modify
the built-in `AssertionError`.
As a result, it is somewhat limited in its capabilities -- it
can only report the *bound* values from that stack frame. That means that this
type of statement works well:
.. code-block:: python
x = f()
y = g()
assert x == y
but this type of statement does not:
.. code-block:: python
assert f() == g()
It will still run, but the prettyassert will tell you that `f` and `g` are
functions, not what they evaluated to. This is probably not what you want.
attribute resolution
--------------------
The assertion inspection will resolve attributes, so that expressions like this
will work as well:
.. code-block:: python
assert x.foo == 1
But note that the attribute `x.foo` will be resolved *twice* in this case, if
the assertion fails. Once when the assertion is evaluated, and again when it is
inspected.
As a result, properties with dynamic values may not behave as expected under
prettyassert inspection.
|
